Environmentally friendly nitrogen-doped carbon quantum dots for next generation solar cells†
Shine on you crazy carbon! In this work, nitrogen-doped carbon quantum dots (N-CQDs) are synthesized using a simple custom atmospheric pressure microplasma. The method is facile, rapid, and environmentally friendly and the N-CQDs can be produced in a few minutes with no need for high temperature, complicated chemical techniques, or surface ligands. The N-CQDs are formed using molecular precursors and can be produced in different solvent mixtures. Material characterization techniques show a high degree of nitrogen doping on the QD surface with the amount of nitrogen depending on initial reaction conditions. The N-CQDs show interesting quantum confined optical properties that depend on the amount of nitrogen incorporation. Importantly, the band energy structure of the N-CQDs is elucidated and they are incorporated into a photovoltaic device as the photoactive layer achieving an extraordinary open-circuit voltage of 1.8 V and a power conversion efficiency of 0.8% (champion device), amongst the highest reported to date for group IV and carbon based quantum dots.